1. Field of the Invention
The present invention relates to ventricular assist devices and, in particular, to implantable ventricular assist devices.
2. Description of the Related Art
It is known to use intra-aortic balloon heart pumps, operating in counterpulsation, to assist heart function. There are however a number of known risks associated with intra-aortic balloon heart pumps including thromboembolism, vessel injury and tissue ischemia. Intra-aortic balloon pumps may also be insufficient to sustain hemodynamics if the left heart is severely injured. There have accordingly been a number of alternative devices developed for assisting heart function in patients with chronic heart failure. For example, U.S. Pat. No. 7,357,771 which issued on Apr. 15, 2008 to Peters et al., and the full disclosure of which is incorporated herein by reference, discloses a device for use in assisting patient heart function. The device comprises an aortic compression means which may be fully implantable, a fluid reservoir, and a pump means adapted to pump a fluid from the reservoir to the aortic compression means so as to actuate the aortic compression means at least partly in counterpulsation with the patient's heart. In addition, the device is adapted to be wholly positioned within the right chest cavity of the patient. The aortic compression means of the device may be curved along its length so as to substantially replicate the curve of the ascending aorta. The device may be easily implanted and there is a low risk of complications
However, devices that repeatedly compress the aorta may damage the aorta and there is accordingly an ongoing need for improved ventricular assist devices.